1. Field of the Invention
The present invention relates to power supplies. Specifically, the present invention relates to the current sharing and redundancy among multiple power supplies.
2. Description of Related Art
In many situations, it is advantageous to combine two or more smaller power supplies together for driving a load instead of providing a single higher powered power supply. In some cases, two smaller power supplies may be less expensive than a single larger power supply. In other situations, it is advantageous to distribute power among several power supplies rather than centralize power in a single power supply. In some electronics enclosures, there may not be enough physical space to accommodate a larger power supply.
Several problems are encountered when multiple power supplies are combined to drive a single load. First, it is important that the load be shared approximately equally between each power supply. Roughly equal load sharing assures that one power supply is not over-driven as a result of the inability of another power supply to equally share the load. Some prior art systems provide multiple power supplies for redundancy purposes. In these systems, however, the load is not typically shared among each power supply. Instead, the load is primarily driven by one power supply or alternatively a redundant power supply. These prior art systems do not provide current sharing among multiple low-cost and off-the-shelf power supplies.
Another problem in a multiple power supply configuration is the need for a circuit to limit the current drawn from a particular power supply. Because a load in a typical electronics system may require more power than a single smaller power supply may provide, a circuit is needed to limit the current provided by any one particular power supply in a set of shared power supplies.
Thus, a better method and apparatus for current sharing among multiple power supplies is needed.